Synthetic absorbable biocompatible polymers are well known in the art. Such polymers are typically used to manufacture medical devices, which are implanted in body tissue and absorb over time. Synthetic absorbable biocompatible polymers include homopolymers, copolymers (random, block, segmented and graft) of monomers such as glycolic acid, glycolide (d, l, meso and mixtures thereof), lactic acid, lactide, .epsilon.-caprolactone, trimethylene carbonate and p-dioxanone. Numerous U.S. Patents describe these polymers including U.S Pat. No. 5,431,679; 5,403,347; 5,314,989; 5,431,679; 5,403,347; and 5,502,159.
There is a constant need in this art for new polymer compositions having improved physical properties when molded or extruded into medical devices and further having excellent in vivo properties. For example, it is known that copolymers of lactide and glycolide have good in vivo properties (U.S. Pat. No. 5,569,250). These materials are also generally known in the art to be single phase, amorphous or semi-crystalline copolymers with melting points exceeding 100.degree. C., and no low melting or immiscible component.
Heat deforming of absorbable devices, such as plates, has also been described in U.S. Pat. No. 5,569,250. However, one drawback of such devices is their lack of a visual cue to aid the surgeon in knowing the precise time that they can begin deforming the device. This is critical to the device, because premature bending or otherwise manipulating it before it has relaxed (i.e., heated above its Tg or Tm) can cause stresses to form in the part, weakening it, especially in clinical situations.
Unfortunately, U.S. Pat. No. 5,569,250 does not recognize that absorbable plates, rods and pins, for example, could be manufactured from a polymeric material that provides a visual cue to a surgeon during surgery to assist him/her in appropriately applying the device to the surgical site.
Therefore, what is needed in this art is a novel device that provides a visual cue during its application (i.e., deformation during heating) to indicate when it can be safely manipulated or shaped.
The surgical devices of the present invention provide a visual cue to surgeons indicating when the surgical device may be contoured or shaped.